LOS ANGELES (AP) Linebacker Alec Ogletree agreed to a four-year contract extension with the Los Angeles Rams through the 2021 season on Thursday night.

The Rams (3-2) reached the deal with Ogletree, their top tackler and a key leader on their defense, early in his fifth season with his only NFL club.

"Alec has evolved into a true leader of our football team," general manager Les Snead said. "His teammates voted him as a captain in back-to-back seasons for a reason, and it's not only because of his production, but his character and resiliency. We look forward to Alec helping our team emerge as a consistent winner for years to come."

The St. Louis Rams drafted Ogletree in the first round out of Georgia in 2013. He took over a key role as their middle linebacker last season, and he has remained prominent during their switch to a 3-4 defense this season under new coordinator Wade Phillips.

"Besides his athletic ability, his leadership is through the roof," Phillips said of Ogletree. "He's a definite leader. I'm sure he got every vote for captain from everybody on the whole team. He's got the great leadership qualities that not a lot of players have. It's just natural with him."

Ogletree leads the Rams with 54 tackles in five games this season, including two sacks. He had 171 tackles by the team's count last season, the fifth-highest total in Rams history.

"The players gravitate to him, and he's a smart player, too," Phillips said. "He can call all of the signals on defense, make all of the adjustments and all those things, so they look to that kind of guy anyway. He's got that leadership value, so I couldn't be more impressed with the guy."

Locking up Ogletree erases one item from Snead's to-do list as he decides how to keep together a defense that consistently has been among the NFL's better units for the past several years.

The Rams still haven't reached a new contract with defensive tackle Aaron Donald, who held out until the day before their first regular-season game. Donald is under Rams control through next season.

Defensive backs Lamarcus Joyner and Trumaine Johnson are both scheduled to be free agents after this season. Johnson is playing his second season on the franchise tender as the Rams' highest-paid player.